Web applications are programs that receive and act on requests in web or other Internet protocols, such as HTTP. It is common for a user to use a web application by using a browser executing on the user's client computer system to send requests in a web protocol via the Internet to a server computer system on which the web application is executing. For example, Yahoo Mail is an email application that is implemented in this way. It is also common for automatic user agents to interact with web applications in web protocols in the same fashion.